Balancing Act

DIY: How to eliminate "ground shadow" from Prius projectors

You may or may not have heard of the infamous "ground shadow" effect that seem to affect only 2010+ Toyota Prius projectors. There are expensive HID kits (expensive by today's standard, that is) with special bulbs that are designed specifically to counteract the so-called "ground shadow" effect. These kits costs anywhere from $80 and up to $150 with special Prius plug-n-play wire harness.

I say that these HID resellers are doing a pretty decent job suckering the average Prius driver who value practicality over the rigmarole associated with the weekend do-it-yourself jobs, more commonly attributed to the tuner subculture. As I've mentioned in my Xentec HID kit review, I've modded the HID bulb to eliminate the "ground shadow" effect. BUT today, while reviewing the photos I've recently taken (i.e. below), I just realized that ALL Xentec kits are shipped with the HID already modded to eliminate ground shadow effect! In other words, no further modding is necessary if you own Xentec-branded bulbs.

If you do not have a Xentec kit or one of those premium Prius-specific HID kits, basically all you need to do is make sure the ground return wire is facing downward (i.e. 6 o'clock position) when you install the bulb into your head lights. Because of the tabs on the H11 bulb, this could pose a problem, i.e. there are two short tabs and one long tab and they need to fit into the headlight bulb socket correctly. A simple solution is to trim down the largest tab so that its size is about the same as the other two:

How to mod your H11 bulb to eliminate "ground shadow" effect

This H11 HID bulb does not require modification, but in the event it does (i.e. the largest tab sitting right below the ground-return wire instead of above the bulb), trim the largest tab along the dotted line.

Before considering any modification at all, orient your H11 HID bulb with the ground-return wire facing down, similar to the photo above. If the two smaller tabs are located on the side and the largest tab is situated above the bulb rather than below the ground-return wire, similar to the photo above, then your HID bulb is "3rd gen Prius projector" ready and requires no additional modification. If the largest tab sits right below the ground-return wire (like in the images below), then follow the proceeding instructions on how to mod your bulbs to eliminate the ground shadow effect.

H11 HID bulb that requires modification. Notice the largest tab is right below the ground-return wire.

If your HID H11 bulbs are plastic, just use a drill or a file and trim down the tab as indicated on the picture above. Be careful and take your time as you do not want to rupture the bulb or damage the ground return wire. If the tabs on your HID H11 bulbs are metal, you will have a challenge ahead of you:

H11 HID bulb with metal tabs that requires modification.

You can use sheet metal cutter to cut through the tabs into correct size or purchase a pair of HID bulbs by Xentec for ~$10.00. Once the largest tab is trimmed, you can install the bulb freely - and rotate it freely until the ground return wire is oriented downward.

That's it, there's no big secret about it. From my experience with a Xentec HID kit so far, they are decent quality. Admittedly not the best in terms of construction, but they do what they are suppose to do. $3x.00 Xentec HID kit vs. $80.00-$150.00 premium "Prius-specific" HID kit, it's really a no-brainer.  And the Xentec HID kits already include the plug-n-play extension cable. Comment with any questions or concerns below.

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